DETROIT (AP) — General Motors’ new CEO and the head of the nation’s auto safety watchdog are headed to Congress to testify about a defect in small cars that is linked to 13 deaths.

In written testimony released ahead of a Tuesday House subcommittee hearing, acting National Highway Traffic Safety Administration chief David Friedman says GM had information connecting defective ignition switches to the non-deployment of air bags, but didn’t share it until last month.

GM CEO Mary Barra will also testify. Committee members will press Barra and Friedman to explain why neither the company nor the safety agency moved to recall millions of small cars with a defective ignition switch, even though GM knew of the problem as early as 2001.

“Sitting here today, I cannot tell you why it took years for a safety defect to be announced in (the small car) program, but I can tell you that we will find out,” Barra said in prepared testimony submitted to the subcommittee.

GM has recalled 2.6 million cars for the faulty switch. That recall prompted GM to name a new safety chief and review its recall processes.

GM continued its efforts to show regulators and consumers that it is more focused on safety, announcing the recall of 1.5 million more vehicles on Monday for a power steering problem.

With Monday’s recall, GM has now recalled 6.3 million vehicles since February. GM estimates the actions will cost it $750 million.

The House hearing — and a separate one Wednesday before a Senate subcommittee — will likely be tense and emotional. At least a dozen family members of victims will attend, wearing blue shirts featuring a photo of 16-year-old Amber Marie Rose, who was killed in a 2005 Cobalt crash, and the words “Protect Our Children.”

Barra will apologize for the loss of life, but may try to limit her answers to Congress, citing an ongoing internal review and government investigations.

“When we have answers, we will be fully transparent with you, with our regulators, and with our customers,” she said in the prepared testimony.

That could test the patience of committee members, who will want to know immediately why GM failed to protect its customers in this case.

Laura Christian, birth mother of Amber Marie Rose, a teenager who died in a 2005 Maryland crash involving a Chevrolet Cobalt, said about 30 family members met with Barra and two GM attorneys Monday night.

All got a chance to tell their stories to GM’s new CEO, but Christian said they got little reaction. “A lot of, ‘I’m so sorry, I’m so sorry,’ ” Christian said.

GM would not comment on details of the meeting.

Congress also wants to know if it needs to strengthen a 2000 law intended to improve communication between automakers and the government.

Here are some questions lawmakers are likely to ask Barra and Friedman, and why:

GM

Q: Why did it take so long to recall these vehicles?

GM’s own timeline, provided to the government, indicates that it knew as early as 2001 that there were problems with the ignition switch in the Saturn Ion. That switch was later used in the Cobalt and other cars. GM eventually learned of accidents and fatalities linked to the switch, and conducted multiple reviews. Yet the cars were only recalled this year. Barra will need to explain why GM didn’t act sooner.

Q: Why was a proposed fix never implemented?

According to a timeline prepared by the House subcommittee, GM engineers developed a fix for the switch in 2004, but it was canceled in 2005 because of its long lead time and cost. Engineers also devised a new key design that would prevent the key from falling out of the ignition, which caused the engine to stall. The fix was approved but later canceled. Lawmakers will want to know why, and who was involved. Barra may not be willing to name names at this point. She has said she only learned of the problem last December, shortly after being named CEO.

— Q. Shouldn’t GM tell owners to stop driving the recalled cars until they are fixed?

GM insists that the cars are safe as long as owners remove anything extra from their key chains, to avoid weighing down the ignition switch. And dealers have permission to give loaner cars to concerned customers until GM can fix their cars. Sen. Richard Blumenthal, D-Connecticut, who sits on the Senate subcommittee, is among those calling for GM to make a stronger statement and tell owners to stop driving their cars immediately.

NHTSA

— Q. Why didn’t NHTSA open an investigation, which is often the first step toward a recall?

As early as 2005, the agency had numerous consumer complaints, service bulletins GM sent to dealers describing the ignition problems and data from a fatal crash in Maryland. And in late 2007, one official recommended investigating reports that air bags in the cars weren’t deploying. An agency panel decided against that because it said a trend wasn’t evident.

— Q. Did NHTSA get enough information from GM?

Safety regulators have sent GM a special order to get more information on the recall, but the automaker’s response isn’t due until Thursday.

In his remarks, Friedman says the agency would have ordered the recall if it had the information GM provided only recently. But safety experts say there was other available information at the time that warranted a recall.

— Q. Does NHTSA have the staff and expertise to deal with the volume of data it’s getting?

After the Ford-Firestone tire recall in the late 1990s, Congress required automakers to report more information to the government about possible defects. NHTSA also gets more than 40,000 complaints per year from drivers. Lawmakers want to know if they agency has the resources to do its job.